johnston



2 SheetsSheet 1.

(No Model.)

L. JOHNSTON. OPERATOR/S SWITGH FOR- TELEPHONE EXCHANGES. No. 585,915.Patented July 6, 1897.

/W. A o I TRANSMITTER a z u. u. o Q! Q? 3 3 J .J 0. n INDUCTION COlLfirowrvz/ (No Model.) 1 2 S1186tS-Sh6t2.

L. JOHNSTON. OPERATORS SWITCH FOR TELEPHONE EXCHANGES. No. 585,915.Patented July 6, 1897v 3 i i a Rma OFF PROP TRANSMI E INDUCTION RECEIVERPOWER GE-ER470 UNITED STATES PATENT OFFICE.

LOUIS JOHNSTON, OF LA CROSSE, WISCONSIN, ASSIGNOR OF THREE-FOURTHS TOIVILLIAM IV. CARGILTJ, FRANK P. HIXON, AND GEORGE II. GORDON, OF SAMEPLACE.

OPERATORS SWITCH FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 585,915, dated July 6,1897.

Application filed March 13, 1897. Serial No. 627,307. (No model.)

To aZZ whom it may cancern: receive a number of the devices which, beingBe it known that I, LOUIS JOHNSTON, a citiduplicates of each other, theinvention will zen of the United States of America, residing be readilyunderstood, so as to be operatively at La Crosse, in the county of LaCrosse, in the applied by the description of a single appa- State of\Visconsin,have invented certain new ratus and its associated mechanismand cirand useful Improvements in Electric-Telecuits. phone CircuitChanging Attachments for Referring to the drawings, A designates aCentral Stations, of which the following is a box or casing made of hardrubber or other specification. suitable non-conductin g material andconsist- IO The invention relates, primarily, to the ing of top andbottom plates12, connected and cam mechanism by which the circuitconnecsupported by side pieces or plates 3 4;, the tion anddisconnection of a telephone with casing being of such size anddimensions as to and from diiferent lines may be effected. adapt it totake and support any requisite The object of the invention is to changenumber of circuit changing mechanisms. I 5 the respective telephoniccircuits through the The casingis preferably made with open ends. mediumof a single circuit changing cam In the top or cover 1 of the casing areformed which controls all of the contacts which may the desired numberof transversely-arranged be interposed in said circuits. slots 5,constituting guide-slots in which the The 1nvent1on Wlll be firstdescribed, and arm or shank of the cam-operator lever 20 thenspecifically pointed out in the claims. moves.

In the devices now used in the art for the B designates acircuit-changing cam made purposes to which the invention is adapted ofsuitable non-conducting material and of a material difficulty orobjection to be oversuch length and breadth as to operatively come isthat the material used in their 0011- contact or press upon thecontact-springs of 2 5 struction is attended with so much friction therespective circuits to be made and broken that after the cams havebeeninuse forashort through the instrumentality of the deprestime they becomeworn out and the intended sions and elevations formed in and on itsuncontacts are imperfectly made and cutder face. On the under surface ofthis cirouts thus caused. It is one of the objects cuit-changing cam areformed a plurality of 30 of the present invention to overcome this decamribs or lugs 13 14: 15 16 17 18 19 and of ficiency, and this is in alarge measure accomcourse havingintermediate corresponding deplished bythe improved constructions of my pressions, substantially as seen inFig. 2 of circuit-changing cam. the drawings, the purpose being that thecam The invention is fully and clearly illusribs or lugs shall serve ascontact means to 3 5 trated in the accompanying drawings, whereeffectthe contact of the circuit-contact springs 8 5 inand that when thecircuit-changing cam is Figure 1 is a perspective view of my imshiftedto make and break other circuits the proved circuit-changing cammechanism desprings shall have room to move upward and tached from thecircuit connections. Fig. 2 out of contact into the recesses ordepressions 0 is an inverted plan view of the circuit-changand break thecircuits, as hereinafter will be 0 ing cam. Fig. 3 is a diagrammaticView of more fully specified. The circuit-changing the inventioninterposed in a circuit using a cam B is supported on rods 8 8, whichslide generator having two lines or complete me in suitable bearings 71formed in the sides of tallic circuit. Fig. 4 is a diagrammatic view thecasing, so that the circuit-changing cam 45 of the invention as appliedto a grounded cirmay be shifted or reciprocated across the cas- 5 cuit.ing and into and out of contact with the de- It will be premised that inthe drawings in sired contact-springs. Fig. 1 but a singlecircuit-changing cam with On the upper face of the circuit-changing itsconnections is shown, but the casing or cam is formed orsecured arack-gear 9 of such 0 supporting-box is shown as being adapted to lengthas to move it the required distance :00

endwisc in either direction. In the casing is secured a suitable hanger10, in which is fulerumed a lever 11, the bar or handle of whichprojects through a guide-slot in the cover of the casing and may beprovided with a handpiece 11 for the grasp.

On the lower end of the switch-lever is formed or secured a segmentalgear 12,which engages with the rack-gear 0 011 the circuitehanging camto move it into and out of contact with the contact-springs of thecircuits to be made and broken. Each lever passes through or alongsideof a curved lockingplate 1), provided with suitable recesses M1 engagedby a spring-tongue i, carried by the lever, whereby the lever and camwill be held in each one of the three positions to which they may bemoved to make and break the respective circuits.

It will be perceived that by shifting the lever the circuit-(hanging camis moved transversely across the casing and into and out of contactwiththe springs, making and breaking the required circuits.

In the bottom of the casing are secured a number of contact springs orpieces a, Z), c, (I, c, and f, having one arm overlying the floor of thecasing and having the other arm depending and projecting through thefloor,substantially as shown, and connected, respectively, to acircuit-wire forming one of the circuits.Inasimilarmannercontact-springs (11, Z), c", d, c, andf areprovided,which overlie the first-mentioned series a to f, inclusive, andhaving one arm extended through the floor of the casing and thecircuit-wire of the other limb or line of the respective circuitsconnected thereto. The contact-arms of the upper series ofcontact-springs are preferably curved upward, as shown, so that thecamlugs on the circuit-changing cam will bear on the arch of the curvesand press the free ends of the springs,whieh normallystand free from thelower contact springs or pieces, down into contact therewith to completeor make the desired circuits.

It will readily be perceived that any form may be given the upper seriesof springs which will adapt them to be pressed down by the cam-lugs 011the circuit-changing cam.

The respective pairs of contacts are arranged in two parallellongitudinally-alined series, and the under surface of the cam has itsprojections and depressions in two series at opposite sides of a centrallongitudinal line, so that the cam will overlie and operate all of theupper contacts of a single mechanism, as set forth in the description ofthe respective circuits.

In Fig. 3 of the drawings the invention is shown in diagrammaticillustration as in operative association with a dynamo-generator systemof circuits, and reference being thereto had it will be seen that whenthe circuitehanging cam is in primary or normal position, being that asshown in Fig. 1 of the drawings, the cam-lugs 13 16 on thecircuitchanger cam are in engagement with contacts a a and c c, whichare pressed in contact, thus closing and completing the plugand cordcircuits used when persons on these line connections are conversing,through wire 11 from (L to c and from (1. through wire 11", throughplugs by wire 10 to contact 0.

To make the circuit required for the operatois talking-circuit, thecircuit-changing cam is shifted a step to the left, so as to bringcamlugs 13,15, 10', and 19 on the springs to close contacts a a, Z) Z),c c, and ff, a circuit be ing thus made through a d '11" 11* to 1: 0,wire 11- to Z) b, from Z) by wire it" to transmitter T, thence by wire11 to contacts/7", and by wire 11) to c c.

\Vhen the operator shifts the circuit-changing cam to make the firstringing-circuit, it is moved another step to the left to bring cam-lug16 to close (1 1;, lug 18 to close 6 e, and lug 17 to close (Z (Z'. Acircuit is then established from the generator Gr by wire 11-", throughc 6, wires 21' 11- to c, the other side of the circuit being from thegenerator G by wire 10, through 17 (Z, wire 11' to wire 11: and then bywire 11 to 0.

hen it is required to move the circuitehanging cam to establish thesecond ringing-circuit, it is moved a third step to the left to bringcam-lugs 14c, 17, and 18 to close contacts a a, (Z d, and 6, making acircuit from generator G, through 11' c 0 11- 10 117 to a, and fromgenerator by wire 11-", through contacts (Z (Z 10 11 11" to (1, thuscompleting the circuit.

The invention is equally well adapted to a grounded circuit, as isillustrated in Fig. t of the drawings. It will be observed thatin thisdemonstration the eontactsff and their connections have been omittedbecause their service has been substituted by the ground at thetransmitter. \Vhen the circuit-changing cam is at normal position inthis arrangement, the cain-lu 13 and 16 are carried over the contacts aa and 1; 1;, closing them, and the line is by athrough wire 11' to plug,from plug to plug by ground, from plug to wire 21: to c, and from c to aby wire 11. through ringoff drop. lVhen the operator connects up thetalking-circuit in this instance, he moves the circuit-changing cam fromnormal position to bring cam-lugs 13, l-t, and 16 to close contacts a a,I) I), and c 0, making a circuit from (1 by 11' to plug I, from c bywire 21" to plug, from d to by 11: and through Z) Z) by 11- 11" throughtransmitter to ground.

when the first ringing or call circuit is made, the operator moves thecircuit-changing cam to bring cam-lugs 1(3 17 18 to close contacts 0 e,(Z (Z, and e e. '0 then have circuit from generator by wire Yb tocontacts 6 c, thence by 10 to contacts 1; c, and by wires 10 and '21" toplug and ring-oil drop to ground.

lVhen the operator shifts the circuit-changing cam to the thirdposition, being the second ringing position, the cam-lu s 1S and 17 aremoved on the contacts (1(1' and 11 171 to ITO close them, and thecircuit is made from generator by wire 205, through d d to a, then to w,to plug, and from a by to ring-off. drop and ground.

It is readilyunderstood that such of the upper series of contact-springs remaining u nused in any of the circuits described lift by theirresiliency into the depressions in the face of the circuit-changing cam,and while in this position for the time being form no part of thecircuits in use.

The operation has been specifically stated in the description respectingthe manipulation of the circuit-changing cam and in the statementsrelative to making and breaking the required circuits, and it willreadily be perceived from these sources that the connection to the lineof a called subscriber is made, as usual, by inserting the proper plugin the line to be connected therewith.

That I claim is 1. In an electric-oircuit-changing mechanism, thecombination with a non-conducting cam having a series of recesses in itsworking face and teeth or projections between said recesses, of a seriesof pairs of contacts arranged one in advance of the other in a planeparallel with the said working face; one member of every pair at thesame side of the series normally tending to spring away from its opposedmating member and toward the said working face of the cam, whereby asthe cam is moved predetermined distances certain of said contacts willspring into the cam-recesses and certain others will be moved intocontact with their mates to make and break the determined circuits,substantially as described.

2. The combination with the circuit-changin g cam herein described,composed of a nonconducting body formed with cam-lugs and depressions onits under face, supportingrods projecting from the ends of the body, arack-gear on its upper face and a lever having a segmental gear meshingwith said rack, of a series of pairs of contacts all controlled by saidprojections and depressions onthe cam.

The combination with a reciprocating circuit-changing cam havingprojections and depressions on its under face, of a series of pairs ofcontact-springs arranged in longitudinal series under the cam; wherebywhen the cam is moved longitudinally a predetermined cam and in the pathof its two sets of projections and depressions.

5. In an electric-telephone-circuit-changing mechanism, the combinationwith the talking, call, and reply circuits having a series of pairs ofcontacts arranged side by side in the same plane, one member of eachpair at the same side of the series tending normally to spring away fromits mate, of a non-conducting cam having its working face overlying saidseries of contacts and formed therein with parallel series of recessesand intervening teeth or projections; whereby as the cam is movedpredetermined distances certain of the contacts will spring away fromtheir mates into the recesses while others will be moved by the camteeth or projections into contact with their mates to break and makedetermined circuits, substantially as described.

6. In an electric-telephone-circuit-changing mechanism, the combinationof a system of telephonic circuits having spring-contacts interposedtherein, one set or series of said contacts consisting of archedsprings, a reciprocatin g circuit-changin g cam formed with lugs andintermediate depressions on its under face,whereby any one of thedetermined circuits may be made and broken, and a lever to shift thecircuit-changing cam.

7. In an electrio-telephone-circuit-changing mechanism, the combinationwith the lower contact-pieces a, b, c, d, e, f, having connectionrespectively to wires forming one side of the circuit, and the uppercontact-springs a, b, c, d, e, andf, having connection respectively towires forming the other side of the circuit, and tending normally tospring away from their mating lower springs of alongitndinally-reciprocating circuit-changing cam B made of a suitablenon-conducting material, formed with lugs on its under face to normallyhold the talking-circuit through contacts a a, c c, by depressingsprings a, c, and lugs and depressions also on its lower face to openand close other circuits in the operative series by depressing certainof the upper springs and allowing others of such springs to move up intosaid depressions.

8. In combination with the contact-pieces a b 0 cl ef, thecontact-springs a, b c d ef, and circuits connecting the same in series,of a circuit-changing cam composed of a suitable non-conducting materialformed with lugs and depressions on its under face disposed to bear onand release the contactsprings and make and break determined circuits,and having a rack-gear on its upper face, sliding supports or bearingsto sustain the circuit-changing cam, and a suitably-fulcrumed leverformed with a segmental gear to engage the rack on the circuit-changingcam to reciprocate it.

9. In electric-telepholie-switch circuits, the

circuitchanging cam herein described, comtransversely across the casing,a lever fulcruined in the casing and formed with a segmental gear On itslower end to engage the rack on the circuit-changing cam and Operate thesame.

LOUIS JOHNS ON.

Witnesses:

GEORGE II. GORDON, MARION G. ANDERSON.

